Along an assembly line, diapers and various types of other absorbent articles may be assembled by adding components to and otherwise modifying an advancing, continuous web of material. For example, in some processes, advancing webs of material are combined with other advancing webs of material. In other examples, individual components created from advancing webs of material are combined with advancing webs of material, which in turn, are then combined with other advancing webs of material. Once the desired component parts are assembled, the advancing web(s) and component parts are subjected to a final knife cut to separate the web(s) into discrete diapers or other absorbent articles. The discrete diapers or absorbent articles may also then be folded and packaged.
In some manufacturing operations, a continuous base web of material is advanced in a machine direction along a converting line. Discrete components and continuous webs are combined with the base web of material to form a continuous length of absorbent articles. In some instances, discrete components are supplied at a relatively consistent separation distance or pitch before being combined with the base web. As such, it may be necessary to accurately control the position at which the discrete components are supplied to help ensure that the components are applied at desired locations on the base web. As such, some control systems may utilize sensors to monitor positions of the components on the base web to determine if the components are properly positioned with respect to the base web. As the base web advances, the components pass by a sensor that detects the presence the components. The sensor provides a feedback signal that corresponds to when a component is detected. A controller receives the feedback signal from the sensor and compares the feedback signal with a setpoint. Based on the comparison, the controller may alter the positions at which the components are added to the base web by temporarily changing the speed at which the components are supplied or by commanding a position move offset.
At relatively low web speeds, the control system may have adequate time to accurately monitor and change the component positions relative to the base web in response to feedback signals from the sensor. However, at relatively high base web speeds, time delays within the control system may result in unstable and/or inaccurate control of component placement. In turn, unstable and/or inaccurate base position control may result in damaged and/or defective absorbent articles. There may be various sources of time delays within the control system, such as time delays associated with the sensor and/or control loops. Some systems may attempt to compensate for the time delays by requiring the converting line to operate at relatively low base web speeds, which results in relatively lower production rates. Other systems may attempt to compensate for the time delays by utilizing high speed sensors, which may add to the complexity and cost of the manufacturing operation.